1. Field of the Invention
This invention pertains to an implant for passing blood flow directly between a chamber of the heart and a coronary vessel. More particularly, this invention pertains to such an implant with an enhanced design for facilitating placement of a transmyocardial conduit into a coronary vessel.
2. Description of the Prior Art
Commonly assigned U.S. Pat. No. 5,755,682 and PCT International Publication No. WO 98/06356 teach an implant for defining a blood flow conduit directly from a chamber of the heart to a lumen of a coronary vessel. An embodiment disclosed in the aforementioned patent and application teaches an L-shaped implant The implant is a conduit having one leg sized to be received within a lumen of a coronary artery and a second leg sized to pass through the myocardium and extend into the left ventricle of the heart. As disclosed in the above-referenced patent and application, the conduit remains open for blood flow to pass through the conduit during both systole and diastole. The conduit penetrates into the left ventricle in order to prevent tissue growth and occlusions over an opening of the conduit
Commonly assigned and co-pending U.S. patent application Ser. No. 08/944,313 filed Oct. 6, 1997, entitled "Transmyocardial Implant", and filed in the name of inventors Katherine S. Tweden, Guy P. Vanney and Thomas L. Odland, teaches an implant such as that shown in the aforementioned patent application with an enhanced fixation structure. The enhanced fixation structure includes a fabric fixation structure. The enhanced fixation structure includes a fabric surrounding at least a portion of the conduit to facilitate tissue growth on the exterior of the implant
Implants such as those shown in the aforementioned patent and applications include a portion to be placed within a coronary vessel and a portion to be placed within the myocardium. When placing a portion of the implant in the coronary vessel, the vessel is incised a length sufficient to insert the implant When placed within the coronary vessel, the implant discharges flow axially into the vessel.
When placing an implant, a portion of the coronary artery is dissected. The dissected portion is incised and the vessel portion of the implant is inserted into the lumen. A stay suture secures the artery to the implant. The stay suture is spaced around the artery and vessel portion a distanced space from the open end of the vessel portion.
In a preferred embodiment, the implant is rigid. After an artery is incised to receive an implant, the artery may collapse in diameter. Also, the artery may have an initial diameter smaller than the outside diameter of the implant The implant may be inserted into the artery to expand the artery. However, this insertion may include a rubbing against the fragile artery wall resulting in damage.